Show the formula and working
This free water meter savings calculator compares the water bill you pay now, based on your home’s rateable value, with an estimate of what you would pay on a water meter, for households in England and Wales deciding whether to switch. Enter your own water company’s metered charges and your household’s water use to see the likely saving or extra cost, the monthly bill and the break even level of use.
Quick answer: A water meter savings calculator multiplies your yearly water use by the metered rates and adds standing charges. Two people using 140 litres each a day use 102.2 m³ a year, about £507.13 at example rates, against a £600 unmetered bill: a saving of about £92.88.
What Is a Water Meter Savings Calculator?
A water meter savings calculator is a tool that estimates your bill on a water meter and compares it with your current unmetered bill, so you can see whether metering is likely to save money.
The formula in plain words: multiply the number of people by the litres each uses a day and by 365, then divide by 1,000 for cubic metres. Multiply by the metered water rate for the water charge. Multiply by the share of water charged as sewerage and by the sewerage rate for the sewerage charge. Add the yearly standing charges. Compare the total with your current bill. Every price is an input, because charges differ between water companies and change each April.
How Do You Use the Water Meter Savings Calculator?
- Enter your Current unmetered bill per year for water and sewerage together.
- Enter People in the home and Litres per person per day.
- Enter the Metered water rate and Metered sewerage rate per cubic metre from your water company’s charges scheme.
- Check the Share of water charged as sewerage and the Metered standing charges per year.
- Read the result and open “Show the formula and working” to see the water and sewerage charges, the total and the break even use.
Will a Water Meter Save Me Money?
A water meter is most likely to save money when there are fewer people in the home than bedrooms, a rule of thumb from the Consumer Council for Water. Small households in large homes often pay a high unmetered bill for little water. The calculator’s break even figure tells you how much each person could use before a meter costs more: in the default example it is 169 litres per person per day.
| People | 100 L each a day | 140 L each a day | 180 L each a day |
|---|---|---|---|
| 1 | 219.69 | 283.56 | 347.44 |
| 2 | 379.38 | 507.13 | 634.88 |
| 3 | 539.06 | 730.69 | 922.31 |
| 4 | 698.75 | 954.25 | 1,209.75 |
| 5 | 858.44 | 1,177.81 | 1,497.19 |
Estimated metered bills per year in pounds at example rates of £2.00 per m³ for water, £2.50 per m³ for sewerage on 95% of water used, and £60 a year of standing charges. These are not any company’s real prices, so enter your own.
Can You Switch Back If a Water Meter Costs More?
In England and Wales, most water companies let you switch back to unmetered charges within a trial period, which the Consumer Council for Water describes as up to two years. Check your own company’s rules before you apply. After the trial ends, or if you move into a home that already has a meter, you normally stay on metered charges. If a meter cannot be fitted, the company may offer an assessed charge instead.
How Much Water Does a Person Use a Day?
Use varies widely, so the tool’s 140 litres per person per day is an example to replace with your own figure. Showers, toilets and washing machines are the largest uses. If you already have a smart or dial meter, two readings a week apart give your real use. For hot water energy, try the electric shower cost calculator, and to compare volumes, the cubic metre calculator.
Worked Example: A Couple in a Three Bedroom House
Example: two people pay an unmetered bill of £600 a year and use about 140 litres each a day. The example metered charges are £2.00 per m³ for water, £2.50 per m³ for sewerage on 95% of the water, and £60 a year of standing charges. These are the tool’s default inputs.
- Water used: 2 x 140 x 365 / 1,000 = 102.2 m³ a year.
- Water charge: 102.2 x £2.00 = £204.40.
- Sewerage charge: 102.2 x 95% x £2.50 = £242.73.
- Metered bill: £204.40 + £242.73 + £60.00 = £507.13 a year, about £42.26 a month.
- Saving: £600.00 minus £507.13 = £92.88 a year. Break even is 169 litres per person per day.
Water Meter Savings Calculator FAQs
How do I work out if a water meter is worth it?
Estimate your yearly use in cubic metres, multiply by your company’s metered water and sewerage rates, and add standing charges. If the total is below your current bill, a meter should save money. The calculator does this and shows the break even use.
Is a water meter cheaper for one person?
Often, yes. One person using 140 litres a day uses about 51 m³ a year, which at the example rates is about £283.56 including standing charges. Compare that with your own unmetered bill and your company’s real rates.
What is the sewerage return percentage?
Companies charge sewerage on the share of metered water they assume goes down the drain, often around 95%. Water used in the garden does not go to the sewer, which is why the figure is below 100%. Check your company’s charges scheme.
How much is a cubic metre of water?
A cubic metre is 1,000 litres. Metered customers usually pay for both water supply and sewerage per cubic metre, so the combined price per cubic metre is what matters. The calculator shows it in the breakdown.
Does it cost anything to have a water meter fitted?
In England and Wales, water companies normally fit a meter free of charge when a household asks for one. Ask your water company about fitting times and whether your home is suitable.
Does this calculator work in Scotland or Northern Ireland?
Not directly. Most households in Scotland pay water and sewerage charges with their council tax, and households in Northern Ireland do not pay separate domestic water charges. The calculator is designed for bills in England and Wales.
Checked October 2026. Sources: Consumer Council for Water, Switching to a meter, Wikipedia, Water metering. All charges in the tool are editable examples, not real company prices.